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Technical Paper

Fretting Fatigue Analysis in Rapidly Solidified Powder Aluminum Alloy

1998-02-23
980698
Fretting fatigue mechanism of rapidly solidified powder aluminum alloy has been studied by model tests and analysis using fracture mechanics. The factors which influences upon fretting scar formation and fatigue crack propagation were the main concerns in the present work. In order to investigate the mechanism of fretting scar formation in detail, fretting wear tests in which small amplitude oscillatory movement occurred in the contact region were carried out. Test results showed that the size of fretting scar increased with increasing tangential force coefficient. Characteristics of fretting fatigue crack propagation were analyzed using fracture mechanics. The fatigue limits under fretting conditions were estimated by connecting the applied stress intensity factor range calculated from applied cyclic stress and tangential force, with the threshold stress intensity factor range of small crack.
Technical Paper

Stereo Vision System for Advanced Vehicle Safety System

2007-04-16
2007-01-0405
In this paper, we will introduce a stereo vision system developed as a sensor for a vehicle's front monitor. This system consists of three parts; namely, a stereo camera that collects video images of the forward view of the vehicle, a stereo ECU that processes its output image, and a near-infrared floodlight for illuminating the front at night. We were able to develop an obstacle detection function for the Pre-Crash Safety System and also a traffic lane detection function for a Lane-Keeping Assist System. Especially in regard to the obstacle detection function, we were able to achieve real-time processing of the disparity image calculations that had formerly required long processing times by using two types of recently developed LSIs.
Technical Paper

Low Friction Property and its Mechanism of DLC-Si Films Under Dry Sliding Conditions

2007-04-16
2007-01-1015
Diamond-like carbon (DLC) films are of significant interest for the automobile field, because they possess the potential to improve friction properties under various sliding conditions. Among the various DLC films, the authors focus on silicon-containing DLC (DLC-Si) films, which exhibit extremely low friction coefficient under dry sliding conditions in an ambient air atmosphere. The aim of this study is to examine the influence of silicon content in DLC-Si films on the friction property of the films, and to clarify the low friction mechanism of the films. The friction test was conducted under dry sliding conditions. It was found that the films have an exceedingly low friction coefficient (about 0.05) ranging in silicon content from 4 at% to 17 at%. In order to examine the low friction mechanism of the films, surface analyses were done on the wear surface of DLC-Si films slid against bearing steel.
Technical Paper

Twenty-Year Review of Polymer-Clay Nanocomposites at Toyota Central R&D Labs., Inc.

2007-04-16
2007-01-1017
More than twenty years have passed since we invented polymer-clay nanocomposites (PCN), in which only a few wt.-% of silicate is randomly and homogeneously dispersed in the polymer matrix. When molded, these nanocomposites show superior properties compared to pristine polymers such as tensile strength, tensile modulus, heat distortion temperature, gas barrier property, and so on. The number of papers on PCN has increased rapidly in recent years, reaching over 500 only in 2005. As the pioneers of the new technology, we will review its history highlighting our works. Epoch-making events of PCN are as follows: In 1985, The first PCN, nylon 6-clay hybrid (NCH), was invented. In 1987, NCH was first presented at the ACS Fall Meetings. In 1989, NCH was presented at the MRS Fall Meetings, firing PCN. In 1989, Toyota launched cars equipped with a NCH part. In 1996, Clay was found to cause a memory effect in liquid crystals.
Technical Paper

Stratification Features of Swirl Nozzle Sprays and Slit Nozzle Spray in DI Gasoline Combustion

2003-05-19
2003-01-1812
The stratification feature of DI gasoline combustion was studied by using a constant volume combustion vessel. An index of stratification degree, defined as volumetric burning velocity, has been proposed based on the thermodynamic analysis of the indicated pressure data. The burning feature analysis using this stratification degree and the fuel vapor concentration measurement using He-Ne laser ray absorption method were carried out for the swirl nozzle spray with 90° cone angle and the slit nozzle spray with 60° fan angle. Ambient pressure and ambient temperature were changed from atmospheric condition to 0.5∼0.6 MPa and 465 K, respectively. Air Swirl with swirl ratio of 0∼1.0 were added for the 90° swirl nozzle spray. Single component fuels with different volatility and self-ignitability from each other were used besides gasoline fuel. The major findings are as follows. High ambient temperature improves stratification degree due to the enhanced fuel vaporization and vapor diffusion.
Technical Paper

Spatio-Temporal Frequency Characteristics Measurement of Contrast Sensitivity for Smart Lighting

2016-04-05
2016-01-1420
This study aims at the development of a projection pattern that is capable of shortening the time required by a driver to perceive a pedestrian at night when a vehicle’s high beams are utilized. Our approach is based on the spatio-temporal frequency characteristics of human vision. Visual contrast sensitivity is dependent on spatiotemporal frequency, and maximum contrast sensitivity frequency varies depending on environmental luminance. Conventionally, there are several applications that utilize the spatio-temporal frequency characteristics of human vision. For example, the National Television System Committee (NTSC) television format takes into consideration low-sensitivity visual characteristics. In contrast, our approach utilizes high-sensitivity visual characteristics based on the assumption that the higher contrast sensitivity of spatio-temporal frequencies will correlate more effectively with shorter perception times.
Technical Paper

Analysis of the Deterioration of Nylon-66 Immersed in GTL Diesel Fuel Part 1. Analysis and Test of Nylon and GTL Diesel Fuel Before and After Immersion

2006-10-16
2006-01-3326
The effect of GTL diesel fuel on organic materials used in fuel delivery systems of vehicles was investigated. Specimens made from 16 kinds of organic materials were immersed in GTL diesel fuels synthesized at Refinery-A and Refinery-B (referred to as GTL-A and GTL-B, respectively) and then subjected to tensile testing. The tensile test results revealed that elongation of the nylon sample immersed in GTL-A was extremely small, about 4% of that of untreated nylon. In the light of this finding, the GTL diesel fuels and nylons before and after immersion test were analyzed in detail using about 20 analysis methods to determine the cause for poor elongation. The following points were found. (1) GTL-A consisted of low molecular-weight paraffins. (2) GTL-A had low molecular-weight i-paraffins. (3) The nylon immersed in GTL-A contained low molecular-weight paraffins. (4) The paraffins in the nylon immersed in GTL-A were richer in i-paraffins than the original GTL-A.
Technical Paper

Universal Diesel Engine Simulator (UniDES) 2nd Report: Prediction of Engine Performance in Transient Driving Cycle Using One Dimensional Engine Model

2013-04-08
2013-01-0881
The aim of this research is to develop the diesel combustion simulation (UniDES: Universal Diesel Engine Simulator) that incorporates multiple-injection strategies and in-cylinder composition changes due to exhaust gas recirculation (EGR), and that is capable of high speed calculation. The model is based on a zero-dimensional (0D) cycle simulation, and represents a multiple-injection strategy using a multi-zone model and inhomogeneity using a probability density function (PDF) model. Therefore, the 0D cycle simulation also enables both high accuracy and high speed. This research considers application to actual development. To expand the applicability of the simulation, a model that accurately estimates nozzle sac pressure with various injection quantities and common rail pressures, a model that accounts for the effects of adjacent spray interaction, and a model that considers the NOx reduction phenomenon under high load conditions were added.
Technical Paper

Development of Compact, High Capacity AWD Coupling with DLC-Si Coated Electromagnetic Clutch

2006-04-03
2006-01-0820
We have developed a high capacity electromagnetic clutch by means of Si-containing diamond-like carbon (DLC-Si) coating. The durability of the new clutch is enhanced up to 8 times higher than that of the conventional one. Such a superior performance is due to several tribological properties of the DLC-Si film and micro morphology on the clutch surface. In particular, the DLC-Si plays a significant role in maintaining the groove shape of the clutch and giving sufficient friction in fluid, which is required for a drivetrain device. Besides, our deposition process (using direct current plasma-assisted chemical vapor deposition) has afforded homogeneous DLC-Si-coated clutches in large quantities. These techniques have enabled us to reduce the number of clutch discs per coupling and achieve a more compact and higher capacity AWD coupling at a lower cost.
Technical Paper

Development of High Performance Three-Way-Catalyst

2006-04-03
2006-01-1061
In conventional gasoline engine vehicles, three-way catalysts are used to simultaneously remove HC, CO and NOx from the exhaust gas. The effectiveness of the catalyst to remove these harmful species depends strongly on the oxygen concentration in the exhaust gas. Deterioration of three-way catalyst results in a reduction in its purification activity and OSC (oxygen storage capacity). In this investigation, additive elements were used to enhance the durability and OSC of the catalyst support material. An optimized formulation of a CeO2-ZrO2 and a ZrO2 material was developed to have excellent durability, improved OSC, enhanced interaction between precious metals and support materials, and increase thermal stability. Using these newly developed support materials, catalysts with increased performance was designed.
Technical Paper

Measurement of Air-Fuel Mixture Distribution in a Gasoline Engine Using LIEF Technique

1992-10-01
922356
The laser-induced exciplex fluorescence (LIEF) technique, currently used to observe mixture formation in a diesel engine, has been applied to a spark ignition (SI) engine and a new equivalence ratio calibration technique has been developed in order that two-dimensional measurements of the equivalence ratio may be made in an operating engine. Spectrally separated fluorescent images of liquid and vapor phase fuel distributions were obtained by adding new exciplex-forming dopants to the gasoline fuel. Dual light sheets from an excimer laser were introduced into one of the cylinders of a 4-valve lean-burn engine, and 2-D images of the mixture formation were recorded at pre-set crank angles during the induction and compression strokes by an image-intensified camera equipped with the appropriate filter.
Technical Paper

Influence of Engine Oil Viscosity on Piston Ring and Cam Face Wear

1993-10-01
932782
The influence of engine oil viscosity on the wear of piston rings and cam faces has been investigated by fired engine tests using a radioisotope (RI) tracer technique. High-temperature and high-shear-rate (HTHS; 150°C, 1O6 s-1) viscosities of the experimental oils prepared are 2.2, 2.4, 2.6 and 3.1 mPa•s. At an oil temperature of 90°C the wear of piston rings and cam faces did not increase, even if the HTHS viscosity was lowered down to 2.2 mPa•s. However, both piston rings and cam faces exhibited an increase in wear below 2.4 mPa•s at 130°C. It was also recognized that valve train wear did not significantly increase with reducing viscosity in the motored engine tests at a temperature of 50°C. From these test results, it was suggested that the oil with the HTHS viscosity of 2.6 mPa•s sufficiently demonstrates the antiwear performance equivalent to that with around 3.0 mPa•s for application to piston rings and cam faces.
Technical Paper

Development of an On-Board Type Oil Deterioration Sensor

1993-10-01
932840
According to the principle of pH measurement, an on-board type engine oil deterioration sensor has been developed. The developed sensor is composed of a Pb and oxidized stainless steel electrodes. The sensor signal shows a good linear relationship to the quasi-pH value of the oil. Especially in the region where the oil deterioration proceeds, the remaining basic additives in the oil is easily estimated from the sensor signal.
Technical Paper

The Development Tool for the Real-Time Fuzzy Control System on a Vehicle

1992-09-01
922128
Recently, there has been many practical applications of fuzzy control. Applications of fuzzy control to vehicles are more effective. However, they require more input and output channels as well as higher speed inference ability than typical applications require. We have developed a tool for developing a fuzzy control system available on a vehicle. The tool consists of a fuzzy inference board and a laptop personal computer with a color display executing a user interface software. The fuzzy inference board can be directly connected with an electronic control unit for vehicle control, and has 10 input channels, 5 output channels and 256 rules. The user interface software mainly provides two functions: 1) The screen editor for membership functions and rules. 2) The real-time monitor for input, output, and grade values when fuzzy inference is executed.
Technical Paper

Variable Axial Composite Lightweight Automotive Parts Using Anisotropic Topology Optimization and Tailored Fiber Placement

2022-03-29
2022-01-0344
This paper presents a design method for continuous fiber composites in three-dimensional space with locally varying orientation distribution and their fabrication method. The design method is formulated based on topology optimization by augmented tensor field design variables. The fabrication method is based on Tailored Fiber Placement technology, whereby a CNC embroidery machine prepares the preform. The fiber path is generated from an optimized orientation distribution field. The preform is formed with vacuum-assisted resin transfer molding. The fabricated prototype weighs 120 g, a 70% weight reduction, achieving 3.5× mass-specific stiffness improvement.
Technical Paper

Relationship between Localized Spine Deformation and Cervical Vertebral Motions for Low Speed Rear Impacts Using Human Volunteers

1999-09-23
1999-13-0010
It is important to more clearly identify the relationship among the ramping-up motion, straightening of the whole spine, and cervical vertebrae motion in order to clarify minor neck injury mechanism. The aim of the current study is to verify the influence of the change of the spine configuration on human cervical vertebral motion and on head/neck/torso kinematics under low speed rear-end impacts. Seven healthy human volunteers participated in the experiment under the supervision of an ethics committee. Each subject sat on a seat mounted on a sled that glided backward on rails and simulated actual car impact acceleration. Impact speeds (4, 6, and 8 km/h), and seat stiffness (rigid and soft) without headrest were selected. During the experiment, the change of the spine configuration (measured by a newly developed spine deformation sensor with 33 paired set strain gauges and placed on the skin) and the interface load-pressure distribution was recorded.
Technical Paper

Numerical Analysis on Multi-Component Fuel Behaviors in a Port-Injection Gasoline Engine

1999-10-25
1999-01-3642
A multi-component fuel vaporization model is developed for numerical analysis of specific fuel component behaviors in port-fuel-injection(PFI) gasoline engines. In order to specify the differences of in-cylinder fuel distribution among its components, three-dimensional calculations of intake flow, spray and vapor motion of each component are performed with respect to engine wall temperature and the distillation characteristics of the fuel. Simultaneous measurements of in-cylinder behaviors of different volatility components in the fuel are also carried out using a laser-induced fluorescence (LIF) technique to validate the calculation results. In both measurements and calculations, the same fuels are used, which are composed of seven or eight components to simulate the distillation characteristics of two kinds of gasoline. The in-cylinder vapor amount of high and low volatility components is compared between the calculations and the experiments.
Technical Paper

Development of a Compact Adsorption Heat Pump System for Automotive Air Conditioning System

2016-04-05
2016-01-0181
In order to reduce the energy consumption of the automotive air conditioning system, adsorption heat pump (AHP) system is one of the key technologies. We have been developing compact AHP system utilizing the exhaust heat from the engine coolant system (80-100 °C), which can meet the requirements in the automotive application. However, AHP systems have not been practically used in automotive applications because of its low volumetric power density of the adsorber. The volumetric power density of the adsorber is proportional to sorption rate, packing density and latent heat. In general, the sorption rate is determined by mass transfer resistance in primary particle of an adsorbent and heat and mass transfer resistance in packed bed. In order to improve the volumetric power density of the adsorber, it is necessary to increase the production of the sorption rate and the packing density.
Technical Paper

Anti- Combustion Deposit Fuel Development for 2009 Toyota Formula One Racing Engine

2011-08-30
2011-01-1983
Toyota participated in Formula One1 (F1) Racing from 2002 to 2009. As a result of the downturn in the world economy, various engine developments within F1 were restricted in order to reduce the cost of competing in F1. The limit on the maximum number of engines allowed has decreased year by year. Toyota focused on the engine performance deterioration due to the combustion chamber deposits. In 2009, Toyota was successful in reducing around 40% of the deterioration by making combustion chamber cleaner in cooperation with ExxonMobil. This contributed to good result of 2009 F1 season for Toyota, including two second place finishes.
Technical Paper

Variation in Nerve Fiber Strain in Brain Tissue Subjected to Uniaxial Stretch

2007-10-29
2007-22-0006
Diffuse axonal injury (DAI) is the most frequent type of closed head injury involved in vehicular accidents, and is characterized by structural and functional damage of nerve fibers in the white matter that may be caused by their overstretch. Because nerve fibers in the white matter have an undulated network-like structure embedded in the neuroglia and extracellular matrix, and are expected to be much stiffer than other components, the strain in the nerve fiber is not necessarily equal to that in the white matter. In this study, the authors have measured strain of the nerve fibers running in various directions in porcine brain tissue subjected to uniaxial stretch and compared them with global strain (tissue strain). The nerve fiber strain had a close correlation with their direction, and was smaller than surrounding global strain.
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